Described below is an operator control device for actuating functional units of a motor vehicle. The operator control device has a touch-sensitive surface and a sensor for detecting a force which can be applied by a user to at least one area of the touch-sensitive surface. An actuator of the operator control device serves for generating a haptic feedback to the user according to the exceeding of a threshold value of the force. Also described below are a motor vehicle and to a method for actuating functional units of a motor vehicle using such an operator control device.
Touch input devices that are provided with haptic feedback are increasingly being used in motor vehicles. This feedback is an artificially generated, that is to say actoric, active haptic feedback. It is in this way made clear to an operator who operates the touch input device that an operator control action as such has been detected, by the actuator bringing about a haptically perceptible movement of the surface that is touched. Furthermore, such touch input devices sometimes include force detection. Therefore, the triggering of functions is not only made dependent on the touching of the touch input device. Rather, the triggering of a desired function also depends on the force applied by the user, in the same way as a user is accustomed to from a mechanical button. For example, the current C class of the automobile manufacturer Mercedes-Benz has a touchpad that is provided with force detection and in which a haptic feedback is artificially generated.
Furthermore, DE 10 2008 036 155 A1 discloses an operator control button arrangement for a motor vehicle with an operator control button. The operator control button has a surface and a pressure sensor. An actuator serves for generating a haptic reaction when the operator control button is actuated. The generation of the haptic reaction by the actuator is made dependent here on whether an operating force reaches a threshold value.
DE 11 2013 002 410 T5 describes a haptic device such as a tablet computer or a smartphone. Here, too, a haptic feedback to a user can take place by a surface moving, vibrating or oscillating. Here, a feedback force may be correlated with a rate at which a compressive force is applied by the user to the surface of the haptic device.
DE 11 2013 002 409 T5 describes an electronic device with a touch-sensitive surface for the display of additional information as a reaction to user contact. When there is contact of a certain intensity, the additional information is displayed, without waiting a predefined delay time. When there is contact of an intensity below a certain intensity threshold, however, waiting initially occurs for the predefined delay time before the additional information is displayed. The device may have tactile output generators, which are coupled with a haptic feedback control unit.
In the case of the operator control devices known from the related art for actuating functional units of a motor vehicle, the haptic feedback is triggered when a threshold value of the force applied by the user is exceeded. In order to keep costs within acceptable limits and also because of technical boundary conditions, there is however always a certain time delay here between the exceeding of the threshold value of the force and the actual triggering of the haptic feedback. This has the consequence that the actual haptic feedback is triggered at a later time, and consequently only when the force is higher than the force threshold. As far as the user is concerned, this gives the impression of an increased triggering force that has to be applied to obtain the haptic feedback. Moreover, this higher triggering force also depends on the actuating speed, or to be more precise on the progression over time of the increase in the force.
This is accompanied by significant disadvantages. On the one hand, the perceived or effective triggering force may be considerably different from the desired threshold value of the force. Furthermore, the perceived or effective triggering force is not constant, but variable, and it is dependent on the type of actuation, that is to say the actuation characteristics.